The present invention relates to a storage system for storing data used by a computer.
In recent years, the amount of data handled by computers has increased dramatically, and hence storage devices for storing data are increasing incapacity. At the same time, large storage systems comprising a plurality of disk devices are being designed to store large volumes of data in an aggregated fashion, rather than dispersing these large volumes of data for storage in a large number of small storage devices.
For example, a storage system disclosed in Japanese Unexamined Patent Application Publication 2003-242039 comprises a plurality of physical devices, and manages storage regions constituted by these physical devices as logical devices. A host computer connected to the storage system can access a logical device by specifying a port ID (a WWN (World Wide Name) for identifying a port uniquely) and a LUN (Logical Unit Number) corresponding to the logical device.
Note that hereafter, a device that is specified by a port ID and a LUN, and recognized as a subject of access from a host computer, will be referred to as a target device.